The present application is based on and claims priority from the following Japanese Patent Applications: 2001-360904, filed Nov. 27, 2001; 2001-360905, filed Nov. 27, 2001; 2001-360906, filed Nov. 27, 2001; and 2002-243592, filed Aug. 23, 2002; the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a synchronous rotary electric machine and, particularly, a flat rotary electric machine to be directly connected to an engine of a vehicle.
2. Description of the Related Art
A synchronous rotary electric machine disposed between a transmission and an engine of a vehicle has to be as flat as possible because of a limited space of the engine compartment of the vehicle. Generally, such a synchronous rotary electric machine has a stator that has a distributed or concentrated winding on the radially inner or outer surface thereof. Such a winding has long coil ends that do not contribute to power generation but to large copper loss. In addition, such a stator winding requires a considerably large space.
Therefore, the present invention has been made in view of the above problem.
A main object of the invention is to provide a compact and efficient flat rotary electric machine.
According to a main feature of the invention, a flat rotary electric machine includes a stator having an annular stator core with a plurality of teeth projecting in opposite directions and an armature winding wound around the stator core, and a field unit including a gutter-like field core having a pair of coaxial cylindrical core members, a plurality of permanent magnets disposed on the cylindrical core members to face the teeth through a first air gap so that one of the permanent magnets on one of the cylindrical core members is disposed between adjacent two of the permanent magnets on the other cylindrical core member and an annular field coil disposed between the cylindrical core members. Each of the cylindrical core member has a plurality of magnet-conductive poles disposed between the permanent magnets to face the stator through a second air gap. The permanent magnets are magnetized so that all the magnetic flux thereof can cross the stator in the same direction. Preferably, the sectional area of the first air gap is larger than the sectional area of the second air gap, and the armature winding may be comprised of a plurality of toroidal coils.
According to another feature of the invention, the stator of the rotary electric machine described above comprises a plurality of tooth-and-yoke units having a tooth which is inserted into one of the toroidal coils and an arc-shaped teeth-and-yoke unit connected to one another by a coupling. The coupling may be comprised of a concavity disposed at one circumferential end of the teeth-and-yoke unit and a convexity disposed at the other circumferential end.
According to another feature of the invention, a flat rotary electric machine includes a stator having an annular stator core with a plurality of teeth projecting in opposite directions and an armature winding, a rotary field core including an open gutter portion having a pair of cylindrical core members respectively disposed to face the teeth and a closed gutter portion having a space, a plurality of permanent magnets disposed on the cylindrical core members to face the teeth through a first air gap so that one of the permanent magnets on one of the pair of cylindrical core members is disposed between adjacent two of the permanent magnets on the other cylindrical core member and a stationary annular field coil disposed in the space of the closed gutter portion to supply magnetic flux thereto.
According to another feature of the invention, a flat rotary electric machine includes a magnet-conductive housing, an annular stator core fixed to and magnetically connected to the housing, a rotary field core having a plurality of magnetic poles circumferentially disposed at intervals of 360 degree in electric angle to face the teeth through a first air gap, a plurality of permanent magnets on the field core to face the teeth through a second air gap so that one of the permanent magnets is disposed between adjacent two of the magnetic poles, a stationary field coil unit fixed and magnetically connected to the housing to be disposed between the stator core and the rotary field core. The field coil unit has an annular field coil for polarizing the magnetic poles and a yoke member facing the rotary field core through a third air gap, and the permanent magnets are magnetized so that all the magnetic flux thereof can cross the stator through the teeth in the same direction.
According to another feature of the invention, a flat rotary electric machine includes a stator having a laminated annular stator core with a plurality of teeth projecting in opposite directions and an armature winding wound between the teeth and a rotary field unit including a gutter-like field core having a pair of parallel core members disposed to face the teeth, a plurality of permanent magnets circumferentially disposed on one of the core members to face the teeth through a first air gap and a plurality of magnet-conductive poles circumferentially disposed on the other of the cylindrical members thereby forming magnetic passage of magnetic flux of the permanent magnets and an annular field coil disposed near the yoke member between the core members so as to polarize the magnet-conductive poles. The field coil polarizes the magnetic poles so as to change the magnetic passages of magnetic flux of the permanent magnets.